core-quality-dead-conditional

Pack: core-quality Default severity: MAJOR Languages: TypeScript, JavaScript Lifecycle: experimental Confidence: 0.95

What it catches

if (...) whose condition is trivially constant: - if (true) / if (false) (and other literal primitives like if (0) / if ('x')) - if (X === X) and if (X !== X) where both sides are textually identical

Why this matters for vibe-coded apps

Pure pivot debris: the developer wrapped code in a gate, decided the gate should always-fire or never-fire, and forgot to remove the wrapper. The branch now either:

• Always runs — the wrapper is noise that hides the actual intent.
• Never runs — the code inside is silently dead but still looks live to the next reader.

Either case misleads the next AI agent or human about which logic is actually executing in production.

Example — flagged

if (true) {                         // always-runs wrapper
  doThing();
}

if (false) {                        // silently disabled
  doExpensiveSetup();
}

if (1 === 1) {                      // tautology
  return 'always';
}

if (x !== x) {                      // impossible
  throw new Error('unreachable');
}

Example — not flagged

We deliberately skip runtime gates that LOOK constant at compile time:

if (process.env.NODE_ENV === 'production') { ... }   // runtime env check
if (CONFIG.debug) { ... }                            // runtime config
if (typeof window === 'undefined') { ... }           // SSR guard
if (x === y) { ... }                                 // distinct identifiers

Suggested fix

Decide what the gate was meant to do:

• Branch should always run → drop the wrapper: doThing();
• Branch should never run → delete the whole if block.
• The gate was real but got over-simplified → restore the actual condition: if (config.flag) { doThing(); }

Suppressing

function pickVariant(): void {
  // Reason: placeholder for an A/B test flag, intentionally always-true today.
  // codemore-ignore-next-line: core-quality-dead-conditional
  if (true) {
    showVariantA();
  }
}

The directive must be on the line immediately before the target. If you put a comment between them, the directive suppresses the comment instead.

Implementation

AST-based. Visits IfStatement nodes; classifies the condition as literal-true, literal-false, tautological-eq, or always-falsy-eq.

Source: `shared/packs/core-quality/core-quality-dead-conditional.ts` Fixtures: `corpus/rules/core-quality-dead-conditional/`